In a typical radio receiver analogue filters eliminate interferers from a received signal and an automatic gain control (AGC) loop ensures that an analogue wanted signal is passed to an analogue to digital converter (ADC) at a suitable level. Subsequent processing of the wanted signal then takes place at baseband in the digital domain. In a highly digitised radio receiver the received signal may be converted into the digital domain earlier in the receiver chain, usually by using a highly oversampled sigma delta ADC, at a point where interfering signals are still present and consequently a large dynamic range is required to characterise the signal. In this case, even with AGC prior to the ADC, the digital processing may require a large word length in order to accommodate the signal in all circumstances.
The present invention seeks to provide improvements in gain control.